Re: [PATCH 2.4.32] Fix AVM C4 ISDN card init problems with newer CPUs
From: Willy Tarreau
Date: Fri Aug 04 2006 - 16:22:59 EST
On Fri, Aug 04, 2006 at 12:39:12PM +0200, Michael Buesch wrote:
> On Friday 04 August 2006 08:56, Willy Tarreau wrote:
> > On Thu, Aug 03, 2006 at 06:56:15PM +0100, Alan Cox wrote:
> > > Ar Iau, 2006-08-03 am 19:53 +0300, ysgrifennodd Jukka Partanen:
> > > > AVM C4 ISDN NIC: Add three memory barriers, taken from 2.6.7,
> > > > (they are there in 220.127.116.11 too), to fix module initialization
> > > > problems appearing with at least some newer Celerons and
> > > > Pentium III.
> > >
> > > Should be using cpu_relax() I think. Its a polled busy loop so you want
> > > other CPU threads to run if possible.
> cpu_relax() implies a memory barrier.
Ok, here's the updated patch for 2.6 using cpu_relax() instead of
mb(), as suggested by Alan and Michael.
> Greetings Michael.